1. Technical Field
The present invention relates to data processing and, in particular, to three-dimensional graphics processing. Still more particularly, the present invention provides a fully programmable three-dimensional graphics engine.
2. Description of Related Art
Three dimensional (3-D) graphics is the creation, display, and manipulation of objects in a computer in three dimensions. 3-D graphics programs allow objects to be represented with width, height, and depth. As 3-D entities, objects may be moved, scaled, rotated and viewed from all angles. 3-D graphics may also allow lighting, texture mapping, and shading to be applied automatically in the rendering stage. 3-D graphics may be implemented using hardware or software or a combination of both.
A graphics accelerator is a high-performance display adapter that provides graphics functions in hardware. When functions are executed on the graphics adapter, the host processor is relieved of much of the processing to render the images on screen. Many display adapters include some acceleration. For 3-D graphics, the operations may include texture mapping, Gouraud shading, and the like.
Many current graphics accelerators use fixed function macros that implement the various graphics vertex and pixel processing tasks in non-programmable, specific logic. Other solutions use both programmable elements and fixed function elements whereby some graphics tasks are implemented in programmable processors while others are relegated to non-programmable, specific hardware logic macros. Currently, the programmable solutions are limited by instruction set size, memory constraints, and the capability of increasing the working set of data elements beyond the size of the intial input data set.
One drawback to the fixed function approach is a lack of flexibility. Fixed function solutions, which can achieve high performance, fail to accommodate new requirements as the graphics Application Programming Interfaces (APIs) evolve. Thus, there is a desire for programmability within the 3-D graphics pipeline, as seen with the industry trend toward “vertex shaders” and “pixel shaders,” existing across the spectrum of graphics offerings available today. These systems must often be redesigned to incorporate new graphics features.
Generally, 3-D graphics accelerators include specific hardware that is costly, consume a large amount of power, and generate a great deal of heat. On the other hand, software acceleration typically places too much of the processing burden on the host processor using compute cycles otherwise reserved for the host application and ultimately not achieving rendering performance typical to hardware graphics accelerators.